Waste converter



H. E. MESCHER WASTE CONVERTER April 2, 1968 4 Sheets-Sheet 1 Filed Oct.8, 1964 INVENTOR HAROLD E. MESCHER BY $048 M ATTORNEY April 1968 H. E.MESCHER 3,376,202

WASTE CONVERTER Filed Oct. 8, 1964 4 Sheets-Sheet 2 INVENTOR HAROLD E.MESCHER ATTORNEY H. E. MESCIHER WASTE CONVERTER April 2, 1968 4Sheets-$heet 5 Filed Oct. 8, 1964 INVENTORV HAROLD EQMESCHER BY fx 5. M

ATTORNEY April 2, 1968 E. MESCHER WASTE CONVERTER 4 Sheets-Sheet 4 FiledOct. 8, 1964 R E H u m E m m M. M E Q. w 0 6 m N L T 0 MA R A f H 2 Y 49 B 2 M 4- 3 l wlll 4 7 2 x 3 36 3 I n||B| L.) [5w ||1|, O 1 4 E Hm M N9 4 3 .J 5 G El Patented Apr. 2, 1968 Ere 3,376,202 WASTE CONVERTERHarold E. Mescher, Pico Rivera, Calif., assignor to Pacific ScientificCompany, San Francisco, Calif, a corporation of California Filed Oct. 8,1964, Ser. No. 402,512 4 Claims. ((31. 2G2-90) This invention relatesgenerally to waste converters as of the Lantz type used for continuouslyproducing charcoal and gas products from Waste or other materials suchas wood, paper, grain hulls, etc., and the invention has reference moreparticularly to novel improvements in such converters.

Waste converters as heretofore constructed generally use rotatingpressure seals at the ends of a heating retort for retaining therelatively high pressure gases generated during the operation of theconverter. Such seals, as heretofore used, tend to leak, resulting inthe escape of high pressure gas, which is not only dangerous andwasteful, but produces condensed tar products around the outside of theseals, which is highly objectionable. Also, in these converters asheretofore made, it has been necessary to prevent leakage at both theloading and discharge ends of the converters, and this is seeminglydifiicult to accomplish satisfactorily.

The principal object of the present invention is to provide a novelimproved converter which is designed to prevent the leakage of gasesfrom the converter, thereby preventing air pollution, possibleexplosions, and the deposition of tars at points of leakage.

Another object of the invention is to provide a novel, improvedconverter wherein suction means is arranged for automaticallywithdrawing generated gases from the converter retort as rapidly as thesame are produced, said converter being so constructed and arranged asto prevent leakage of generated gases through the loading and dischargeends of the retort.

A feature of the present invention is to provide a novel improvedconverter of the above character that is so designed that the retortpressure in the converter is substantially equal to or but slightlyabove atmospheric pressure, whereby the rotating end seals are no longersubject to appreciable pressure and it is relatively easy to prevent gaslosses from the retort under all operating conditions.

Another feature of the present invention is to provide a novel improvedconverter of the above character employing a flare stack and responsivemeans for controlling the gas discharge blower of the converter wherebygases are withdrawn from the converter at a rate depending entirely uponthe rate of production of such gases therein, the said removed gasesbeing withdrawn for use in heating the converter retort or for otheruses.

A still further feature of the present invention is to provide a novelconverter of the above character wherein high pressure seal loading andunloading systems are eliminated, thereby greatly simplifying thestructure of the converter.

These and other features and advantages of the present invention will bemore apparent after a perusal of the following specification taken inconnection with the accompanying drawings, wherein:

FIG. 1 is a partial vertical longitudinal sectional side view of a novelconverter of the present invention;

FIG. 2 is a sectional view taken along line 22 of the structure shown inFIG. 1A;

FIG. 3 is a perspective view of this furnace taken from the rear; I

FIG. 4 is a schematic view similar to FIG. 3 showing the arrangement ofthe fuel piping;

FIG. 5 is a fragmentary enlarged view of the structure circled at SinFIG. 1; and

FIG. 6 is a fragmentary enlarged view of the structure circled at 6 inFIG. 1A.

Similar characters of references are used in the above figures todesignate corresponding parts.

Referring now to the drawings, the reference numeral 1 designates theinsulated casing or housing of the converter, which casing is supportedon a frame 2. Casing 1 is provided with propane or natural gas burners92 (see FIG. 3) for producing =heat therewithin. Burners 92 are adaptedto be supplied with propane or other gas from lines 3 during the initialstart-up of the converter, and thereafter the casing 1 is heated withgenerated retort gas as will further appear, the temperature withininsulated casing 1 being of the order of 1500 F. during operation.

A metallic cylindrical rotatable retort 4 is contained within the casing1 and extends longitudinally thereof and has its ends projecting throughconforming apertures in the ends of the casing. The end portions ofretort 4 have support collars 5 and 5 fixed thereon, the circularperiphery of which collars ride in grooves provides in supportingrollers 6 carried by yokes 7 and 7, yokes 7 being carried by a supportframe 8 which in turn is supported by rollers 9, longitudinally movableon brackets 10 supported upon the frame 2. Yokes 7 are supporteddirectly upon the frame 2. Rollers 9 permit thermal expansion andcontraction of the retort 4 in use, the forward end of the retort movingin and out of the conforming aperture provided in easing 1 through whichthe retort extends. Frame 8 also supports the rear end of a closedconveyor housing 11 that has its forward portion supported upon a yoke12 which in turn carries a support roller 13 riding on a stand 14.Within the conveyor housing 11 is contained a movable plate conveyor 15driven by chain 16 that in turn is driven from a conveyor motor 17through reduction gearing 18. The plate conveyor 15 receivescarboniferous material such as wood chips, coal, sawdust, trash, etc.,from a hopper 19 positioned near the forward end of the conveyor. Thecarboniferous material 20 feeds by gravity down the hopper 19, thishopper being supplied from a suitable source such as by use of a bucketconveyor 62. The height of the material 20 within the hopper 19 ismaintained sufiicient so as to seal off the hopper and the closedconveyor housing 11 from the outside air to thereby seal off thecylindrical retort 4, which in use has an internal pressure very closeto that of the atmosphere, so that it is not necessary to have a highpressure seal as such at the entrance to hopper 19, but the height ofthe material 20 within the hopper is sufiicient to provide an adequateseal since the retort does not contain an appreciable gas pressure inuse.

Upper and lower bindicators 21 and 21, somewhat spaced apart, aremounted upon the hopper 19 and have cruciform vanes 22 projecting intothe interior of the hopper, which vanes are rotated by motors within thebindicator housings through slip clutches. The vanes 22 of thebindicator 21 are normally above the level of material 20 in hopper 19and so rot-ate continuously whereas vanes 22 of bindicator 21', beingnormally surrounded by material 20, do not rotate. Should vanes 22 ofbindicator 21 stop rotating due to material 20 piling too high in hopper19, the material conveyor motor will be stopped, since these bindicatorsare connected into the control circuit of the conveyor 62 supplyingmaterial 20 to the hopper. On the other hand, vanes 22 of the bindicator21 are normally stationary and should these vanes rotate, a relayconnected with bindicator 21 will operate to speed up the conveyor 6-2supplying the hopper, so that the material is maintained at a levelsubstantially as shown in FIG. 1 of the drawings, thus preventing accessof outside air to the retort 4- and also preventing escape of gases fromthis retort through conveyor housing 11 and hopper '19 to the outsideair.

A vibrating guide plate 23 is pivoted at 24 within the hopper 19 andcooperates with a lift drag plate 25 and the moving plates of conveyorto aid in moving the material onto the conveyor 15 in use. Lift dragplate is pivoted at 26 and as the conveyor plates move by, they agitatethis drag plate and also the guide plate 23 to jar the carboniferousmaterial onto the plate conveyor, while at the same time preventing thematerial from working its way down the conveyor housing 11 to bind thedrive sprocket 27. A material feed plate or vane 28 is positioned withinthe hopper 19 so as to aid in guiding the material upon the conveyor andprevent the same from jamming against the rear wall of the hopper inuse. Since the hopper 19 is sealed upon the casing of the conveyorhousing 11 and as this housing is sealed at its upper end to therotating retort 4, as will shortly appear, it will be noted that theintake to the retort is a sealed system. Although not capable ofretaining or excluding high pressures, it retains retort operatingpressures which are close to atmospheric pressure, so that no gases leakfrom the interior of the retort, nor do they leak into the retortthrough the material feed system just described.

The retort 4 is provided with an annular end plate 29 at its forwardend, to the inner periphery of which is secured an entrance tube 30,into which the conveyor 15 discharges the carboniferous material to betreated, this material dropping onto a helical vane 31 positioned withinthe forward end portion of the retort 4, the vane 31 serving to catchthe material from the conveyor and push it towards the rear of theretort, while the same rotates, as will further appear. In order toprovide a low pressure seal between the rotatable retort 4 and thestationary conveyor housing 11 there is provided on the entrance tube 30a bracket supported annular flexible disc 32 (FIGS. 1 and 5) which maybe of stainless steel of light gauge such as 26 gauge, for example. Theperipheral portion of this flexible disc 32 is secured between anannular notched plate 33, that is slidably supported on brackets 34carried at regular angularly spaced points on the end plate 29, and abearing ring 35 as of stainless steel that is secured by angularlyspaced studs 36 having nuts 37 clamping plate 33 and ring 35 againstflexible disc 32. A plate member 38 attached to the conveyor housing 11carries a ring 35 to the outer portion of which is attached a bearingring 40 as of brass which bears against the steel bearing ring 35.

Compression springs 41 surround the free ends of studs 36 and areconfined therebetween and nuts 43 carried by studs 42 fixed to theannular end plate 29 of the retort. Springs 41 serve to press thebearing plate 35 against bearing ring 40, thereby providing a lowpressure seal while permitting relative rotation of bearing plate 35 andbearing ring 40. The stationary ring 39 is provided with an annularcooling water space 44 through which cooling water can be circulated toprevent overheating of the bearing surfaces due to the heat withinretort 4. The flexible disc 32 permits any slight misalignment or wobbleof the rotating retort 4 in use with respect to the stationary conveyorhousing 11.

The retort 4 is rotated by means of a retort drive motor 45 drivingthrough reduction and chain speed gearing 46 and sprocket chain 47,idlers 48 and large sprocket 49, carried by support collar 5 fixed uponand surrounding the rear exposed end of the retort 4. The rear endportion of the retort 4 is sealed similarly to its forward end portion,the seal comprising a flexible disc 32' (see FIG. 6) similar to disc 32,having its inner portion attached to the retort 4 and its outer portionsecured between an annular plate 50 and bearing ring 35 as of stainlesssteel through the intermediary of washer 51 by use of studs 36' threadedinto ring 35' and having nuts 37 hearing on rotating retort 4 in usewith respect to the stationary dis charge chute 52. Carrier brackets 63attached to retort 4 protect flexible disc 32 against injury in use.

The retort 4 as shown in FIGS. 1 and 2 carries a series of mutuallyspaced interior longitudinally extending vanes.

53 which help to elevate the material 20 within the retort as thismaterial advances rearwardly from helical vane 31 towards the rear ofthe retort. The vanes 53 are relatively shallow, but act to elevate thematerial in the retort as the material advances, so as to obtain uniformheating thereof. Since the retort is heated all around its circumferencewithin the furnace casing 1, this heating action serves to rapidly driveout moisture from the advancing material, most of which moisture entersa central gas discharge tube 54 having its open forward end near thefront of the retort. The retort. is also provided internally with anumber of mutually spaced annular shallow dams 55 which serve to aid inretaining the material within the retort just sufficiently to insure thecomplete reduction to charcoal or other material within the retort andthe elimination of gases and moisture therefrom. The drum retort 4preferably tilts slightly towards its rear end to aid in moving thematerial from the forward end of the retort to the rear end, i.e.,towards the discharge chute 52. This tilt may be of the order of to therunning foot. The retention time of the material within the retort isprimarily governed by the slope of the retort and the speed ofrevolution thereof, this speed being variable by varying the variablespeed drive 46, for example, depending upon the nature of the materialbeing treated.

By the time the material 20 reaches the discharge end of the retort 4,it has been turned into carbon and is discharged into chute 52 bygravity. This chute 52 is kept filled to a point somewhat above thebottom of the discharge end of the retort with discharged charcoal 20,so as to provide a seal between the retort and the lower screw conveyor56, thereby preventing the entrance of air, which would cause the heatedcharcoal to burn. The level of the material 20' is maintained bybindicator 21', whose vanes are normally stationary, but if they shouldrotate, the output of the bindicator 21 acts upon the control circuit ofthe conveyor motor driving the screw conveyor 56 so as to cause thisconveyor to slow down so as to maint tain the level of the charcoal asdesired.

The central longitudinal extending gas discharge tube or conduit 54 ismaintained under slight suction by means of a blower 57, whose inlet isconnected to a plenum chamber 58 projecting inwardly from the rear endwall of chute 52. In practice, approximately all the steam and 50% ormore of the combstible gas driven from the material 20 will enter thesuction line of tube 54 near its forward end, thus aiding in preventingany smoke and gas from entering the conveyor housing 11, and this fluidwill pass therealong to the rear of the retort, and after passingthrough blower 57, is discharged into a pipe 59, from whence it isconveyed to a scrubber 60 and from thence it passes into a storage tank61 for distribution and use as desired.

In order to control the amount of gas withdrawn through discharge tube54 so that the proper pressure is maintained within retort 4, a damperor butterfly valve 63 is contained within the discharge pipe 59. Thisvalve is operated by a motor 64 operating through linkage 65, motor 64being controlled in turn in accordance with the pressure and/ ortemperature within the retort 4. To control this motor by temperature, aflare stack 66 may be employed, positioned above the discharge chute 52and supplied with gas through a feeder flue 67. A pilot light 68supplied with natural or propane gas is positioned beneath the openflare 66' of flare stack 66 so as to ignite gases leaving the top of thefeeder flue 67, which flue contains a manually operable butterfly valve69. Positioned upwardly within the stack 66 is located a temperaturesensing bulb or thermostat 70 which is connected as by lead 72 into thecontrol circuit of motor 64. As the pressure within the retort 4gradually rises, the escaping gas from feeder flue 67 ignited by pilotlight 68 will burn higher and higher within the stack 66, therebyraising the temperature of thermostat 70, which will in turn controlmotor 64 so that as the temperature rises, this motor will openbutterfly valve 63 more and more, whereby more and more fluid will bedrawn from the retort 4 to maintain the temperature therewithinsubstantially constant.

If desired, a pressure controller 71 can be used for controlling themotor 64, this pressure controller consisting of casing 73 havingbaffles 74 therewithin and provided with low and high pressure diaphragmswitches 75 and 75', these switches serving to control motor 64 so thatdamper 63 is positioned to maintain a substantially constant pressurewithin retort 4.

During the initial start-up of the converter, the housing 1 is heatedinternally by the burners 92 supplied with propane or natural gasthrough line 3, as shown in FIG. 3. However, after the converter hasbeen operating for a while and gas is being produced, the heating can bedone by the gas so produced, and to accomplish this, produced gas linesor conduits 76 and '76, extending outwardly of discharge chute 52, havetheir inner ends projecting into the retort 4 and their open inclinedinner ends are adapted to be closed by valve plates 77, pivoted at 78and actuated by linkage 79, pivoted at 80. The shaft 80' of pivot 80extends externally of chute 52 and is connected by linkage 81 to a motor82. Motor 82 may be controlled manually or may be controlledautomatically as by thermostat 70 or pressure controller 71. Thus, whenthe motor 82 is operated actuating linkages 81 and 79 the valves 77 areopened by moving the same to the position shown in dot dash lines inFIG. 1, whereupon gases within the retort pass outwardly through gaslines 76 and 76' and into the Venturi mixers 83 and 83 located at thefront and at the rear of the converter (see FIG. 4) which mixers aresupplied with air from a blower 84 passing air into lines 85 and 85, themixed air and fuel gas then passing into front burners 86 and 86' andinto rear burners 87 and 87. As specially shown in FIG. 2, these burnersare hollow tubular members with longitudinally depressed burner portions88 which are apertured to enable the mixture of air and fuel to passinto the interior of the casing 1, the ignition of which by pilot lights89 serves to heat the retort 4.

In operation, the action of the converter is continuous, in that rawmaterial is continuously fed into hopper 19 under control of bindicators21 and 21', passes through conveyor housing 11 into the cylindricalretort 4, through which it passes slowly, the moisture and gasescontinued within the material being driven off. The majority of thesteam and 50% or more of the combustible gases Will enter the gasdischarge tube 54, the mouth of which is positioned near the front ofthe retort 4, where most evaportion of moisture takes place. A shield 90is positioned in advance of the inlet of tube 54 and overlying the same,so as to prevent material from dropping down from the upper part of theretort and falling into the intake of this tube.

The gas leaving the rear end of the retort 4 and passing into gasfurnace lines 76 and 76 is quite dry and burns readily within theburners 86, 86', 87, and 87', this action taking place after theconverter has been operating sufiiciently to produce the desired gasoutput under the heating action of propane or natural gas burners 92,whereupon these burners 92 can be turned off and generated fuel used toheat the retort thereafter. The charcoal produced by the process, asheretofore pointed out, is discharged into screw conveyor 56 and storedfor future use,

whereas the gas feeds out of discharge pipe 59 at a rate determined bythe temperature and pressure within the retort as heretofore explained,which then passes into scrubber 60 and storage tank 61 for future use.Since the temperature and pressure Within the retort is controlledcontinuously by the action of thermostat 70 and/or pressure controller71, no high internal pressure develops, and hence there is no undesiredgas leakage at the retort end seals. Thus, it will be seen that theconverter is entirely automatic in its operation and produces charcoaland gas by-products Which are used to heat the converter to maintain itsoperation or stored for future use or refinement. It will be noted thatthe sealed conveyor housing 11, the retort 4 and the discharge chute 52form a closed, substantially inverted U- configuration which forms asealed structure to prevent the escape of generated gases or inlet ofunwanted air.

Since many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A material converter for continuously producing charcoal and gasproducts, comprising a casing containing a heated rotatable retort,means for supplying raw material such as wood chips, paper, grain hulls,etc., to said retort and removing charcoal material therefrom, means forsealing said retort, conduit means provided within said retort andextending exteriorly thereof for conducting combustible gases therefrom,the drier portion of said gases being used for heating said retort, saidconverter having valve means connected in said conduit means forcontrolling the flow of said gases through said conduit means, controlmeans communicating with the interior of said retort and connected tosaid valve means for controlling the latter, whereby the gas pressurewithin said retort is retained substantially at atmospheric pressureduring operation, a flare stack adjacent said retort connected forreceiving gas therefrom, and means for igniting the gas in said flangestack, said control means comprising a temperature sensitive elementwithin said flare stack connected for controlling the operation of saidvalve means.

2. A material converter as claimed in claim 1 wherein said control meanscomprises a pressure controller connected with the interior of saidretort, said controller having pressure operated switches controlled bythe gas pressure within said retort, and motor means controlled by saidswitches and connected for actuating said valve means.

3. A material converter for continuously producing charcoal and gasproducts, comprising a converter casing, a substantially horizontalcylindrical retort rotatable within said casing having input and outputends, means within said casing for heating said retort to a temperatureof the order of 1500 R, an enclosed, inclined material supply conveyorhousing having its upper end portion sealed to the input end of saidretort and depending therefrom for delivering waste raw matreial such aswood chips, paper, grain hulls, etc., to said retort, a charcoaldischarge chute having its upper end portion sealed to the output end ofsaid retort and depending therefrom, said sealed material conveyor andsealed discharge chute serving to withstand substantially atmosphericpressure obtaining within said retort during operation of saidconverter, the lower end portion of said material conveyor housing andsaid charcoal discharge chute being selfsealed solely by the materialpassing therethrough, whereby gases generated within said retort cannotescape to the atmosphere nor can atmospheric air enter said retortduring operation, a gas discharge conduit extending within said retortand having its input end positioned near the input end of said retortfor conducting steam and moist combustible gases therefrom, valve meansconnected in said conduit for controlling the rate of flow of gas fromsaid retort, and control means connected to said retort responsive togas pressure thereWithin for controlling said valve means so as tomaintain the interior of said retort at substantially atmosphericpressure in use.

4. A material converter as defined in claim 3 comprising an additionalgas discharge conduit extending into the output end of said retort forremoving dry gas therefrom for use in heating said retort, additionalvalve means connected to said additional discharge conduit forcontrolling the flow of gas therethrough, and motor 8 means :foractuating said additional valve means, said control means beingconnected for controlling said motor means.

References Cited UNITED STATES PATENTS 2,111,663 3/1938 Graemiger21417.62' 1,945,530 2/1934 Karrick 2O2136 1,631,024 5/1927 Fisher 200-521,497,333 6/1924 Helbig 20115 10 2,973,306 2/1961 Chick et a1. 201lJAMES H. TAYMAN, JR., Primary Examiner.

1. A MATERIAL CONVERTER FOR CONTINUOUSLY PRODUCING CHARCOAL AND GASPRODUCTS, COMPRISING A CASING CONTAINING A HEATED ROTATABLE RETOR, MEANSFOR SUPPLYING RAW MATERIAL SUCH AS WOOD CHIPS, PAPER, GRAIN HULLS, ETC.,TO SAID RETORT AND REMOVING CHARCOAL MATERIAL THEREFROM, MEANS FORSEALING SAID RETOR, CONDUIT MEANS PROVIDED WITHIN SAID RETORT ANDEXTENDING EXTERIORLY THEREOF FOR CONDUCTING COMBUSTIBLE GASES THEREFROM,THE DRIER PORTION OF SAID GASES BEING USED FOR HEATING SAID RETORT, SAIDCONVERTER HAVING VALVE MEANS CONNECTED IN SAID CONDUIT MEANS FORCONTROLLING THE FLOW OF SAID GASES THROUGH SAID CONDUIT MEANS, CONTROLMEANS COMMUNICATING WITH THE INTERIOR OF SAID RETORT AND CONNECTED TOSAID VALVE MEANS FOR CONTROLLING THE LATTER, WHEREBY THE GAS PRESSUREWITHIN SAID RETORT IS RETAINED SUBSTANTIALLY AT ATMOSPHERIC PRESSUREDURING OPERATION, A FLARE STACK ADJACENT SAID RETORT CONNECTED FORRECEIVING GAS THERFROM, AND MEANS FOR IGNITING THE GAS IN SAID FLANGESTACK, SAID CONTROL MEANS COMPRISING A TEMPERATURE SENSITIVE ELEMENTWITHIN SAID FLARE STACK CONNECTED FOR CONTROLLING THE OPERATION OF SAIDVALVE MEANS.